Apparatus for timing



Jan. 18, 1938. w BOWER 2,105,470

APPARATUS FOR TIMING Filed Oct. 8, 1935 INVENTOR Ward E. Bower ATTORNEY Patented Jan. 18,. 1938 UNITED STATES PATENT OFFICE APPARATUS FOR TIMING Ward E. Bower, Washington, D. 0.

Application October 8, 1935, Serial No. 44,072

Claims. (01. 161-15) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to a method of and aponce frequency interval-between any twoor more paratus for timing and more particularly to a standard frequency sources together with means method of and an apparatus for measuring the for accurately recording the beats produced. time elapsing between the occurrence of two suc- Other and further objects of this invention will cessive events in which the unit of time (one be apparent from the following specification and 5 second) may be divided into ten thousand or less the accompanying drawing in' which: e ual parts, Fig. 1 shows schematically and partially in sec- In modern usage we can no longer rely upon tion one of the revolving members and certain of any one gear in a gear train in a clock mechanism the other associated elements of the system;

as having a constant angular velocity with re- Fig. 2 is a plan view of the disc 3 showing one 10 spect to the-escapement fly wheel at the head of arrangement of the apertures therein; this train. Neither may we expect a sufllciently Fig. 3 is a schematic circuit diagram of the elecconstant reciprocating oscillation in the escapetrical circuits of the system; and ment fly wheel of a clock gear train even though Fig. 4; is a top plan view of a timing mechanism a constant force is continually applied to the employing three independently driven rotating 15 driving gear. This is due simply to the inaccumembers together with means for determining racies unavoidable in the dividing head mechawhen any two of the members are rotating in nism of the milling machine or dies used in prophase and/or in synchronism with each other. clucing said gears introducing errors that can not Referring to the accompanying drawing in be accepted in modern demands. which like characters of reference indicate the In order to eliminate gear train clockwork as same parts in the different figures, I denotes the far as possible, it has been proposed to derive shaft of a synchronous motor of the La Cour timing impulses from a. sub-multiple harmonic wheel type, 2 is the rotating armature fixed to the generator of the thermionic tube typeactuated by shaft, 3 is a disc fixedly mounted on the shaft oscillations from a relatively stable source. How-- and adapted to rotate therewith while 4 is the ever, due to the inherent tendency of such har- A. C. excited field of the motor which is selecmonic generators to slip to another frequency and tively connectible by switches S4 to a source of the inflexibility of such systems, amethod of constant frequency (source not shown) of some and apparatus for subdividing a constant freknown periodicity as for example 1,000 cycles per quency into any desired ratio of subdivided fresecond or to the output of amplifier I2, hereafter quency to frequency being subdivided has been described. devised together with means for producing audi- In the present case the armature 2 is notched ble sounds at the subdivided frequency and with 100 notches so that the shaft I will rotate means for recording the subdivided frequency acexactly 10 revolutions per second when thefield l curately to a fractional part of the time period of is excited from a source of 1,000 cycles per second. one complete cycle of the undivided or fundasemicircular cams KI, K2, and K3 are fixed to mental frequency, so that each fractional part shaft I to rotate therewith. Cams KI and K2 are of one complete cycle bears a true relation one to arranged at 180 phase relation one to the other. the other at all times and shows no wending efwhile cam K3 is timed at 90 to cams KI and K2. feet when referred to other portions of the cycle Surrou d n the Shaft l adjacent to the p and so subdivided. bottom of disc 3 are situated two stationary cir- One of the principal objects of this invention is cular electromagnets EI and E2. A very light to provide a method of and an apparatus for den R f p m ne c ma erial such as iron is termlning the total number of whole cycles and situated above the disc 3 between the pole faces the fractional parts of a cycle of alternating curof electromagnets El and E2 and is free to fioat rent of known frequency that are generated bebetween the c 3 and et The i R tween the happening of t successive e nt b is induced to remain in concentric conjugation tween which it is desired to measure the elapsed with the Stationary members and the revolving ma members by having an annular flange F turned Another object of this invention is to provide a on s 3 a d around which R s d posed. a 50 means for subdividing a constant frequency of construction that is conventional and not a part known periodicity into any desired ratio of subof applicant's invention. The ring R is engraved divided frequency to frequency being subdivided. with a fiducial line of reference parallel to its A further object of this invention is to provide equatorial radius. The electromagnets El and E2 a means for accurately determining the diilerhave windings LI and L2 included therein and 55 these windings are covered partially by circular discs 5 and 6 of magnetic material. Associated with one side of the disc 3 is a source of light 8 and opposite thereto is a member 9 containing an aperture beyond which there is a reflecting prism l0 adapted to reflect a ray of light emanating from the source 8 through an aperture 1 in the disc 3, through the aperture in the member 9, to the reflecting prism l0, and thence to a photo-electric cell H which is connected in the input circuit of an amplifier l2 the output of which may be connected to various means such as the relay i3, recorder H, or converter 15, or in accordance with the disclosure in my Patent 2,000,010, May '7, 1935, it may be utilized to drive the armature 2, as indicated in Fig. 1. Adjacent to another point on the periphery of the disc 3 is located an air jet i6 and an apertured member cooperating therewith. The members l6 and I1 may be moved radially of the disc 3 in order to select any desired row of the holes I therein and likewise the source of light 8, apertured member 9, and reflecting prism l3 ,may be moved radially of the disc to cooperate with the rows of holes I on the various radii of the disc. In a preferred embodiment of the system, the disc 3 is pierced with 1,000 equally spaced holes on its largest possible radius, 800 on its next largest radius, 500 on the next, on the next, 10 on the next, and l on the inner radius. With this arrangement and with the disc 3 rotating at a speed of 10 complete revolutions per second I readily have a means of multiplying or dividing the original frequency F0 (1,000 cycles) by any decimal fraction of two significant figures or whole numbers within the physical possibilities of the mechanical device. Adjacent to the disc 3 there is located a stationary scale U for cooperation with the revolving ring R. At I! there is located a camera by means of which photographs may be made to record the instantaneous positions of the rotating discs.

A plan view of the revolving disc 3 is shown in Fig. 2 with several rows of holes located at different radii. It is to be understood that the revolving discs may be made easily detachable from the driving shaft I and that various discs may be made with various numbers of holes of various sizes and shapes to suit special requirements. In Fig. 3 the cams Ki, K2, and K3, the electromagnet coils LI and L2 are shown connected in circuit. One terminal of coil Ll is connected to the high potential side of battery B2 while the other terminal thereof is connected to the relay contact G, one terminal of coil L2 is connected to the high potential side of B2 while the other terminal is connected to the relay contact H. Associated with the relay contacts G and H is a relay armature or tongue T which may be connected by means of switch S3 to the low potential side of battery B2. The armature T has associated therewith relay coils L3 and L4 for moving the armature either to the contact G or the contact H. Coil L3 has one terminal thereof connected to the armature T and switch S3 while the other terminal thereof is connected to a spring 22 normally actuated by cam K2. Coll L4 has one terminal thereof connected to the relay armature T and to switch S3 while the other terminal thereof is connected to the spring 2| normally actuated by cam KI. Associated with spring 2| there is a contact C against which spring 2| is caused to lie when the protruding part of the cam Kl is against spring 2 I. Contact D is associated with spring 22 and a circuit is made from spring 22 to contact D when the cam K2 presses the spring 22 thereagainst. Switches SI and S2 are connected to the high potential side of battery Bl. The switches Si and S2 connect the battery Bl to contacts D and C, respectively. The low potential side of the battery BI is connected to one side of the switch S3. Associated with the cam springs 2| and 22 is a hand-operated cam or button 20 adapted to raise the springs 2| and 22 off of the cam surfaces of cams KI and K2 and to hold them against the respective contacts C and D when the cam 20 is turned to the position indicated by dotted lines in Fig. 3. Associated with cam K3 is a spring 23 and contact 23. When the cam K3 is in the position shown, contacts 28 and 29 are closed. Contact 23 is connected by way of the electric counter I9 to the relay contact H while spring 23 is connected to the high potential side of battery Bl.

In the above description of Figs. 1, 2, and 3 a single unit only is shown. In Fig. 4, three rotating discs are shown at 3, 3|, and 32. These discs are mounted on separate shafts driven independently by three sources of driving frequency. In addition to the holes 1 in disc 3 as disclosed hereinbefore, the discs 3, 3i, and 32 in the arrangement as shown in Fig. 4 are provided with apertures 23, 24, and 25, respectively, and the discs are arranged to overlap one another so that it may be determined whether any two of the discs are rotating in phase and in synchronism. Counters 26 and 21 are associated with the discs 3| and 32 in the same manner that counter i9 is associated with disc 3.

The operation of the system is as follows: The field I of the synchronous motor is excited from a standard source of known frequency, (in the present case preferably 1,000 cycles) so that the notched armature 2, shaft l, and disc 3 rotate at exactly 10 revolutions per second. It is desired to derive an audible note having a frequency of some harmonic of 10 cycles per second, the air jet I6 and the member H are moved radially of the disc 3 until they are aligned with that row of holes corresponding with the desired harmonic. A stop-cock associated with jet I6 is then opened and a musical note may be heard corresponding to the frequency at which the air jet is interrupted. When an audible indication of the division of time is not required and it is desired to obtain a frequency based upon the rotational speed of the disc 3 as a standard, the source of light 3, and members 9 and ID are moved to the position desired radially of the disc 3 in which case the rotating disc 3 chops the light falling on photoelectric cell II at some frequency determined by the speed of rotation of the disc 3 and the number of holes at the radius selected. The light impulses falling on photoelectric cell ii are amplified by amplifier l2 and passed to any one or all of the devices l3, i4, and |5. Recorder I4 is used to record the 'equal intervals of time of passing of light between the revolving disc 3 and the selective apertured member 9 or between any two or more revolving discs when the number of revolutions per second of one of the discs is known. In the high frequencies where it is not possible to record photographically, the amplified electrical pulses can be used to charge or discharge an inductive and capacitive circuit thus converting the electrical pulses into sinusoidal oscillations which are the source of alternating current of very deflnite frequency. Where it is desired, the oscillations after being passed through one or more tuned circuits may be applied to energize the field l of the synchronous motor in a manner somewhat similar to that disclosed in my Patent No. 2,000,010 granted May 7, 1935. By selecting the proper number of apertures, the system may be used to derive frequencies in the region of 10 to 200 pulses per second which may be used as standard timing units. Any desirable whole even or odd number of pulses per revolution of the disc may be selected and the interval between each two succeeding pulses is equally spaced.

Where it is desired to time accurately to l/10,000th of a second events occurring on the same or different days, the arrangement is employed as follows: The button or hand-operated cam 20 (Fig. 3) is turned to raise the springs 2i and 22 in contact with contacts C and D, respectively. The switch S3 is closed while the synchronous motor is being driven from the standard source. Switch SI is then closed in which case relay winding L3 is energized, attracting relay armature T to contact G, closing the circuit of electromagnet winding Ll which causes the ring R to be attracted towards El and stopped. In this position R is held firmly against El by current flowing through Ll; the counter I9 is now read as it is in central position. Switch Si is then opened and the ring R remains in its upward position against the stationary scale because the armature T is of the type that stays in the position to which it was last moved. After the counter 19 has been read and the relation of the graduations on ring R and scale U has been noted and it is desired to use the device for timing an event, as for instance, a race, the switch S2 is closed to begin the timing. When S2 is first closed the relay winding L4 is energized by way of switch $3 from battery BI and switch $2, This causes the attraction of relay armature T to contact H and the consequent energization of the electromagnet winding L2 which is energized from battery 132 by way of contact H, armature T, and switch S3. Upon the energize.- tion of electromagnet winding L2 the ring R will leave El in an attempt to go to E2 by virtue of the magnetic pull exerted thereon. It will be drawn up against the rotating disc 3 substantially instantaneously and caused to revolve at the same angular velocity as the disc. Each time the disc 3 makes one complete revolution, the cam K3 completes the circuit with the electrical counter l9 and measures a complete revolution. Before the termination of the race or the interval being timed, the switch S2 is opened and at the exact end of the time interval being measured the switch Si is closed at which time relay winding L3 energizes to raise the armature T and stop the further operation or the counter 19 and complete a. circuit to electromagnet winding Ll to cause the ring R to be drawn away from the revolving disc 3 and stopped. The reading of the time elapsed may now be taken by reading the counter l9 and deducting therefrom the number of revolutions indicated by it at the beginning of the timing and adding to this quantity the fractional part oil a revolution indicated by the ring R. With the ring R divided into 100 equal parts by radial lines and revolving 10 times per second, it is seen that each complete division thereon corresponds to an elapsed time of 1/1,000th of a second. By further subdividing the ring R or providing a vernier scale on the member U, it is possible to readily divide a second into 10,000 equal parts with a high degree of accuracy.

In order to check possible errors due to differences in the time of transit of the ring R to or from El or E2, the button or hand-operated cam 20 may be turned to such a position as to permit the springs 2i and 22 to ride upon the cams Kl and K2, respectively, in which case the ring R may be attracted to El and read. The switch S2 may be closed in which case L3 and L4 will be alternately energized, thus causing the relay armature T to lie against contact G for one revolution and then against contact H for the next revolution in which case the ring R will be thrown alternately from electromagnet El to electromagnet E2. When the ring R has passed back and forth from electromagnet El to electromagnet E2 100 times or 1,000 times or any other desired number of times, the switch S2 may be opened and the ring R may be read with respect to the scale U in order to determine the cumulative error of slippage incident to a great number of transits. In one embodiment of the device as constructed by applicant, this error due to slippage of the ring was found to be less than 1;/40,000th of a second for a complete transit to and from the rotating disc.

In this arrangement three synchronous motors with identical or similar mechanism as above set forth may be used, all of which can be mounted symmetrically together but independent of the same frequency control. Each one or any two may diiier from 1,000 cycles per second by a difl'erence determined solely by the mechanical and electrical characteristics oi the members themselves. In the arrangement shown in Fig. 4

the positioning of the revolving members is such as to bring any two revolving discs one over the other. The discs may have round, square or rectangular holes or specially designed slits, scrolls or spirals in them to produce any desired shaped pulsating wave form in amplifier i2 and as sociated networks. 0n discs 3, 3i, and I2, I use one slit in each disc. Ii the angular velocity of each disc is different, it is so arranged that these slits come into conjugation at certain intervals of time. These coincident intervals are called beats and may be accurately measured in terms of the rotation oi. one disc against standard time. At a time when the slits are becoming adjacent, a light may be made to pass through the increasing opening and operate a system similar to 8, 9, 10, 11, 12, 13, 14, and 15. The impulses generated may be counted visually or electrically.

A further refinement is shown in Fig. 1, where it is a camera located in such a position as to be able to photograph all three revolving members at any instant of time and which can be com trolled by any one of the three electrical counters previously described, or by any associated circuit or II, M, or converter l0, or manually.

Fig. 4 depicts the view of the three synchronous motor discs 3, ii, and 32 together with their respective counters i8, 20, and 21 which are within the focal limits of the camera lens. It is quite obvious that from two pictures of this surface taken with a definite interval at time elapsing, one can record with an accuracy of one part in ten thousand the whole and fractional part of the number oi revolutions these discs have made during that known elapsed time With this procedure the accuracy oi my timing mechanism may be determined.

This invention may be manufactured and used by or for the Government of the United States without the payment 01' royalties thereon.

" iii L165.

What is claimed is:

1. In a device for measuring time to a small ir ction of a second, a continuously rotating disc rotating at a predetermined definite speed, a relatively light magnetic ring coaxially mounted in juxtaposition to said rotating disc, said magnetic ring being provided with indicia thereon, a first electromagnet for moving said magnetic ring into close physical contact with said rotating disc so that said magnetic ring turns with said rotating disc, a stationary element, a second electromagnet associated with said stationary element for moving said magnetic ring away from said rotating disc into close physical contact with said stationary element, a stationary member bearing a fiducial line of reference located adjacent to said magnetic ring, means for energizing the first electromagnet for moving said magnetic ring into contact with said rotating disc at the beginning oi. a time interval to be measured, and means for deenergizing the first electromagnet and energizing the second electromagnet for moving said magnetic ring away from said rotating disc and into physical contact with said stationary element at the end of a time interval to be measured.

2. In a device for measuring time to a small fraction of a second, a continuously rotating disc rotating at a predetermined definite speed, a relatively light magnetic ring coaxially mounted in juxtaposition to said rotating disc, said magnetic being provided with indicia thereon, a first electromagnet for moving said magnetic ring into close physical contact with said rotating disc so that said magnetic ring turns with said rotating a stationary element, a second electromagt associated with said stationary element for Gl iilg said magnetic ring away from said rotatg disc into close physical contact with said ationary element, a stationary member beara iiducial line of reference located adjacent c said magnetic ring, means for energizing the st electromagnet for moving said magnetic ring contact with said rotating disc at the ber niing of a time interval to be measured, means -or deenergizing the first electromagnet and energizing the second electromagnet for moving said magnetic ring away from said rotating disc and into physical contact with said stationary tent at the end of a time interval to be measnd means for registering the whole numevolutions made by the rotating disc bethe energization of said first electromag- "1d the energization of said second electroo. In a device for measuring time to a small fraction of a second, a continuously rotating disc J 'ng at a predetermined definite speed, a relatively light magnetic ring coaxially and fioatably disposed in juxtaposition to said rotating disc, said magnetic ring being provided with indicia thereon, a first electromagnet for moving said magnetic ring into close physical contact with said rotating disc so that said magnetic ring turns with said rotating disc, a stationary element, a second electromagnet associated with said stationary element for moving said magnetic ring away from said rotating disc into close physical contact with said stationary element, a stationary member bearing a fiducial line of reference located adjacent to said magnetic ring, means for energizing the first electromagnet for moving said magnetic ring into contact with said rotating disc at the beginning of a time interval to be measured. and means tor deenergizing the first electromagnet and energizing the second electromagnet for moving said magnetic ring away from said rotating disc and into physical contact with said stationary element at the end of a time interval to be measured.

4. In a. timing device for measuring time to a small fraction of a second, a continuously rotating disc rotating at a predetermined definite speed, a relatively light magnetic ring coaxially and fioatably disposed in juxtaposition to said rotating disc, said magnetic ring being provided with indicia thereon, a first electromagnet for moving said magnetic ring into close physical contact with said rotating disc so that said magnetic ring turns with said rotating disc, 8. stationary element, a second electromagnet associated with said stationary element for moving said magnetic ring away from said rotating disc into close physical contact with said stationary element, a stationary member bearing a fiducial line of reference located adjacent to said magnetic ring, means for energizing the first electromagnet for moving said magnetic ring into contact with said rotating disc at the beginning 0! a time interval to be measured, means for deenergizing the first electromagnet and energizing the second electromagnet for moving said magnetic ring away from said rotating disc and into physical contact with said stationary element at the end of a time interval to be measured, and means for registering the whole number of revolutions made by the rotating disc between the energization of said first electromagnet and the energization of said second electromagnet.

5. In a timing device, a rotatable shaft, a disc fixed on said shaft to rotate therewith, a stationary electromagnet disposed adjacent each face of said disc, a light paramagnetic ring fioatably mounted between said disc and one of said electromagnets, and means to energize and deenergize said electromagnets in accordance with events to be timed.

WARD E. BOWER. 

